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The first term of an arithmetic sequence is −22 . The common difference of the sequence is 5.

What is the sum of the first 30 terms of the sequence?

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 Apr 28, 2020
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Here the common difference is positive, so we know that we're adding 5.

 

The first thirty terms would be -22, -17, -12, -7, etc. until the 30th term.

 

The formula for calculating the first n terms, initial term is a1

Sn = n(a1 + an)/2 = n[2a1 + (n - 1)d]/2

 

From this, we get 1515 :)

 Apr 28, 2020

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